Import and visualize a raster map of LCZ
Data: the Redon territory from the european LCZ map produced by the WUDAPT project
The World Urban Database and Access Portal Tools is a project which aims at creating LCZ with earth observation data. The details of the project and the related papers can be found on the website of the project: https://www.wudapt.org/
The map we are going to use in this vignette is the European LCZ map, as described in the paper available at the following url: https://doi.org/10.1371/journal.pone.0214474
As this method is one of the most used we included the map tif in the embedded data of the package.
Load a territory from a raster map and a bounding box
The first step is to define a bounding box of the territory of
interest. The lczexplore comes with vector data for the Redon Territory,
a rural town of Brittany, France. The importLCZvect is a generic import
function for vector data, and when the ouput argument is
set to bBox, it returns the bounding box of the input
layer. Any bounding box of the bounding box class of the package
sf can be used to crop the raster map. We can use a
bounding box created from a vector file. Or create a bounding box from
its coordinates. The package osmdata also offers the getbb() function
which allow to get the bounding box from a location if it is named in
openStreetMap.
redonBbox<-importLCZvect(dirPath=paste0(system.file("extdata", package = "lczexplore"),
"/multipleWfs/Redon"), file="osm_lcz.fgb",column="LCZ_PRIMARY",output="bBox")
# Example with osmdata function getbb, not run, to avoid installation of the package
# library(osmdata)
# redonBbox<-getbb("Redon", format_out = "sf_polygon")The second step is to import the raster map and use the previous bounding box to crop the territory of interest. The importLCZraster function performs this in a simple call:
redonWudapt<-importLCZraster(system.file("extdata", package = "lczexplore"),
fileName="redonWudapt.tif", bBox=redonBbox)
#> Warning: attribute variables are assumed to be spatially constant throughout
#> all geometriesThe resulting object is an sf file, the pixels of the geotiff have been transformed into geometries. The input file must be a geotiff, whose CRS will be read by the function.
library(sf)
#> Linking to GEOS 3.14.1, GDAL 3.12.2, PROJ 9.7.1; sf_use_s2() is TRUE
st_crs(redonWudapt)
#> Coordinate Reference System:
#> User input: ETRS89-extended / LAEA Europe
#> wkt:
#> PROJCRS["ETRS89-extended / LAEA Europe",
#> BASEGEOGCRS["ETRS89",
#> ENSEMBLE["European Terrestrial Reference System 1989 ensemble",
#> MEMBER["European Terrestrial Reference Frame 1989"],
#> MEMBER["European Terrestrial Reference Frame 1990"],
#> MEMBER["European Terrestrial Reference Frame 1991"],
#> MEMBER["European Terrestrial Reference Frame 1992"],
#> MEMBER["European Terrestrial Reference Frame 1993"],
#> MEMBER["European Terrestrial Reference Frame 1994"],
#> MEMBER["European Terrestrial Reference Frame 1996"],
#> MEMBER["European Terrestrial Reference Frame 1997"],
#> MEMBER["European Terrestrial Reference Frame 2000"],
#> MEMBER["European Terrestrial Reference Frame 2005"],
#> MEMBER["European Terrestrial Reference Frame 2014"],
#> MEMBER["European Terrestrial Reference Frame 2020"],
#> ELLIPSOID["GRS 1980",6378137,298.257222101,
#> LENGTHUNIT["metre",1]],
#> ENSEMBLEACCURACY[0.1]],
#> PRIMEM["Greenwich",0,
#> ANGLEUNIT["degree",0.0174532925199433]],
#> ID["EPSG",4258]],
#> CONVERSION["Europe Equal Area 2001",
#> METHOD["Lambert Azimuthal Equal Area",
#> ID["EPSG",9820]],
#> PARAMETER["Latitude of natural origin",52,
#> ANGLEUNIT["degree",0.0174532925199433],
#> ID["EPSG",8801]],
#> PARAMETER["Longitude of natural origin",10,
#> ANGLEUNIT["degree",0.0174532925199433],
#> ID["EPSG",8802]],
#> PARAMETER["False easting",4321000,
#> LENGTHUNIT["metre",1],
#> ID["EPSG",8806]],
#> PARAMETER["False northing",3210000,
#> LENGTHUNIT["metre",1],
#> ID["EPSG",8807]]],
#> CS[Cartesian,2],
#> AXIS["northing (Y)",north,
#> ORDER[1],
#> LENGTHUNIT["metre",1]],
#> AXIS["easting (X)",east,
#> ORDER[2],
#> LENGTHUNIT["metre",1]],
#> USAGE[
#> SCOPE["Statistical analysis."],
#> AREA["Europe - European Union (EU) countries and candidates. Europe - onshore and offshore: Albania; Andorra; Austria; Belgium; Bosnia and Herzegovina; Bulgaria; Croatia; Cyprus; Czechia; Denmark; Estonia; Faroe Islands; Finland; France; Germany; Gibraltar; Greece; Hungary; Iceland; Ireland; Italy; Kosovo; Latvia; Liechtenstein; Lithuania; Luxembourg; Malta; Monaco; Montenegro; Netherlands; North Macedonia; Norway including Svalbard and Jan Mayen; Poland; Portugal including Madeira and Azores; Romania; San Marino; Serbia; Slovakia; Slovenia; Spain including Canary Islands; Sweden; Switzerland; Türkiye (Turkey); United Kingdom (UK) including Channel Islands and Isle of Man; Vatican City State."],
#> BBOX[24.6,-35.58,84.73,44.83]],
#> ID["EPSG",3035]]The LCZ are expressed with several conventions. We chose to use 1 to 10 for the urban and 101 to 107 for the land-use types.
One can then use standard R functions to explore the data.
summary(redonWudapt)
#> EU_LCZ_map geometry geomID
#> 6 :104 POLYGON :208 Length:208
#> 104 : 56 epsg:3035 : 0 Class :character
#> 102 : 35 +proj=laea...: 0 Mode :character
#> 3 : 11
#> 8 : 1
#> 101 : 1
#> (Other): 0
summary(redonWudapt$EU_LCZ_map)
#> 1 2 3 4 5 6 7 8 9 10 101 102 103 104 105 106 107
#> 0 0 11 0 0 104 0 1 0 0 1 35 0 56 0 0 0One can see, for instance that no pixel of the imported territory set to one of the following levels: 1, 2, 4, 5, 7, 10, 103 or 105, or that the most present LCZ type is 104, with 1116 pixels.
Visualize the LCZ map with the function showLCZ
Once the dataset has been loaded into an R object of class
sf, the function showLCZ produces the map of
it’s repartition. The argumentsf sets the input dataset,
the column of the LCZ types is passed to the argument
column. The argument wf is just a string that
will be used to produce the title of the plot, and it allows the user to
specify which workflow produced the input data.
For standard LCZ types, one sets the argument
repr="standard", and the function will recognize levels
from 1 to 10 and from 101 to 107. It is the recommended choice. But
standard representation will also accept levels from 11 to
17 and from A to G.
The following code shows an example of color choice.
